How Can I Create Comma-Separated Lists of Values from Groups in DB2?
Generate comma separated output by group in DB2
DB2 built-in function LISTAGG
can concatenate column values with the same grouping, separated by commas. This is useful when you need to merge data within groups.
For example, suppose a table contains two columns, ID and Role, and three rows have the same ID but different Role values. The goal is to concatenate the Role values for each ID into a comma-separated list.
The LISTAGG
function introduced starting with DB2 LUW 9.7 accomplishes this:
SELECT ID, LISTAGG(Role, ', ') AS Roles FROM myTable GROUP BY ID;
This query will generate the desired output:
<code>ID Roles ---------- 4555 2,3,4</code>
It is worth noting that you can use the WITHIN GROUP
clause and the ORDER BY
statement to specify the order in which values are concatenated. This allows for greater control over the order in which values are listed:
SELECT ID, LISTAGG(Role, ', ') WITHIN GROUP (ORDER BY Role ASC) AS Roles FROM myTable GROUP BY ID;
In this case the output will be:
<code>ID Roles ---------- 4555 2,3,4</code>
LISTAGG
Provides a convenient way to aggregate and join data in DB2, enabling efficient group-based string operations.
The above is the detailed content of How Can I Create Comma-Separated Lists of Values from Groups in DB2?. For more information, please follow other related articles on the PHP Chinese website!

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